U.S. patent number 4,997,034 [Application Number 07/137,193] was granted by the patent office on 1991-03-05 for heat exchanger.
This patent grant is currently assigned to Minnesota Mining and Manufacturing Company. Invention is credited to Vaughn B. Grannis, Frank S. Schroder, James E. Steffen.
United States Patent |
4,997,034 |
Steffen , et al. |
March 5, 1991 |
**Please see images for:
( Certificate of Correction ) ** |
Heat exchanger
Abstract
A heat exchanger including a plate of heat conductive material
having a first major face and second major face. An array of a
plurality of integral heat transfer elements projecting from the
first face and a fan to cause a flow of a heat transfer fluid past
the heat transfer elements thereby transferring heat between the
heat exchanger and the heat transfer fluid.
Inventors: |
Steffen; James E. (Woodbury,
MN), Grannis; Vaughn B. (Inver Grove Heights, MN),
Schroder; Frank S. (Afton, MN) |
Assignee: |
Minnesota Mining and Manufacturing
Company (Saint Paul, MN)
|
Family
ID: |
22476209 |
Appl.
No.: |
07/137,193 |
Filed: |
December 23, 1987 |
Current U.S.
Class: |
165/104.34;
165/104.33; 165/185; 165/41; 165/122; 361/695 |
Current CPC
Class: |
F28D
1/024 (20130101); B64G 1/50 (20130101); F28F
13/125 (20130101); F28F 3/048 (20130101); F28F
3/022 (20130101); F28F 9/001 (20130101); F28F
2275/085 (20130101) |
Current International
Class: |
B64G
1/50 (20060101); F28F 9/00 (20060101); B64G
1/46 (20060101); F28F 3/00 (20060101); F28D
1/02 (20060101); F28F 3/04 (20060101); F28F
13/12 (20060101); F28F 13/00 (20060101); H01L
023/467 (); F28D 015/00 () |
Field of
Search: |
;165/104.33,104.34,185,41,122 ;361/383,384
;432/77,81,219,221,223,254.2 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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207677 |
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Jan 1987 |
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EP |
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78566 |
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Dec 1894 |
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DE2 |
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659774 |
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May 1938 |
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DE2 |
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861141 |
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Jan 1953 |
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DE |
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2099803 |
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Mar 1972 |
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FR |
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368816 |
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Apr 1963 |
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CH |
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206044 |
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Apr 1986 |
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SU |
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529037 |
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Nov 1940 |
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GB |
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Other References
Coles, R. E., IBM Technical Disclosure Bulletin, vol. 6, No. 2,
7/1963..
|
Primary Examiner: Davis, Jr.; Albert W.
Attorney, Agent or Firm: Kinney & Lange
Claims
What is claimed is:
1. A heat exchanger comprising:
a plate made of heat conductive material having a first major face
and a second major face;
a plurality of diamond-shaped heat transfer elements projecting
from the first face and integral with the plate, the elements being
arranged in a wedge-shaped array; and
a panel substantially parallel to and spaced apart from the first
face and defining a plenum space that encloses the wedge-shaped
array of the heat transfer elements, the plenum space including a
half rib located between a pair of arrays.
2. The heat exchanger of claim 1 wherein the plate is circular and
has a center, the wedge-shaped array is radially disposed about the
center.
3. The heat exchanger of claim 1 wherein the heat transfer elements
are longitudinal projections
4. The heat exchanger of claim 1 wherein the heat conductive
material includes aluminum.
5. The heat exchanger of claim 1 wherein the heat conductive
material includes copper.
6. The heat exchanger of claim 1 further including means to move a
fluid in communication with the plenum space.
7. The heat exchanger of claim 1 wherein the wedge-shaped array
includes a plurality of rows and column of the heat transfer
elements.
8. The heat exchanger of claim 7 wherein the heat transfer elements
each have four faces, the plurality of rows have an axis, the
plurality of columns have an axis, and the axis of the plurality of
rows and the axis of the plurality of columns are each parallel to
faces of the heat transfer elements.
9. The heat exchanger of claim 1 wherein the heat exchanger
includes four quadrants each with a pair of wedge-shaped arrays
forming a circular heat exchanger about a center point.
10. The heat exchanger of claim 9 wherein the plate is circular,
the plenum spaces extend outwardly from the center, and further
including means to move a fluid located proximate the center of the
plate.
11. The heat exchanger of claim 1 wherein the second major face of
the heat exchanger is smooth.
12. A heat exchanger for use in a triple containment system wherein
heat production occurs in a first container and a first heat
transfer fluid is disposed within a second hermetically sealed
container with the heat transfer fluid being in fluid communication
with an exterior surface of the first container, the second
hermetically sealed container being disposed within a third
container that is hermetically sealed from an outside environment,
the heat exchanger comprising:
conductive plate means having a first plurality of spaced apart
pins extending from a first surface and a second plurality of pins
extending from an oppositely facing second surface, the first
plurality of pins being in heat transfer relationship with the
environment and the second plurality of pins being in heat transfer
relationship with the heat transfer fluid in the second container
and wherein the plate means includes first and second discrete
plates having first and second smooth surfaces facing each other in
conductive heat transfer relationship;
first means for moving the heat transfer fluid within the second
container past the second plurality of pins; and
second means for moving air from the environment past the first
plurality of pins.
13. A heat exchanger for use in a triple containment system wherein
heat production occurs in a first container and a first heat
transfer fluid is disposed within a second hermetically sealed
container with the heat transfer fluid being in fluid communication
with an exterior surface of the first container, the second
hermetically sealed container being disposed within a third
container that is hermetically sealed from an outside environment,
the heat exchanger comprising:
conductive plate means having a first plurality of spaced apart
pins extending from a first surface and a second plurality of pins
extending from an oppositely facing second surface, the first
plurality of pins being in heat transfer relationship with the
environment and the second plurality of pins being in heat transfer
relationship with the heat transfer fluid in the second container
and wherein the plate means includes first and second discrete
plates having first and second smooth surfaces facing in physical
contact;
first means for moving the heat transfer fluid within the second
container past the second plurality of pins; and
second means for moving air from the environment past the first
plurality of pins.
14. The heat exchanger of claim 13 wherein the first means to move
fluid is a fan.
15. The heat exchanger of claim 14 wherein the second means to move
air is a fan.
16. A heat exchanger for use in a triple containment system wherein
heat production occurs in a first container and a first heat
transfer fluid is disposed within a second hermetically sealed
container with the heat transfer fluid being in fluid communication
with an exterior surface of the first container, the second
hermetically sealed container being disposed within a third
container that is hermetically sealed from an outside environment,
the heat exchanger comprising:
conductive plate means having a first plurality of spaced apart
pins extending from a first surface and a second plurality of pins
extending from an oppositely facing second surface, the first
plurality of pins being in heat transfer relationship with the
environment and the second plurality of pins being in heat transfer
relationship with the heat transfer fluid in the second container
and wherein the pins of the first plurality of pins each have a
diamond-shaped cross section;
first means for moving the heat transfer fluid within the second
container past the second plurality of pins; and
second means for moving air from the environment past the first
plurality of pins.
17. The heat exchanger of claim 16 wherein the pins of the second
plurality of pins each have a diamond-shaped cross section.
18. A heat exchanger comprising:
a plate made of heat conductive material having a first major face
and a second major face;
a first wedge-shaped array of a first plurality of spaced apart
heat transfer elements projecting from the first face and integral
with the plate wherein the first plurality of spaced-apart heat
transfer elements are pins having a diamond-shaped cross
section;
a second wedge-shaped array of a plurality of spaced apart heat
transfer elements projecting from the second face and integral with
the plate;
means to move a first heat transfer past the first array; and
means to move a second heat transfer fluid past the second
array.
19. A heat exchanger comprising:
a plate made of heat conductive material having a first major face
and a second major face;
a first wedge-shaped array of a first plurality of spaced apart
heat transfer elements projecting from the first face and integral
with the plate;
a second wedge-shaped array of a plurality of spaced apart heat
transfer elements projecting from the second face and integral with
the plate; wherein the second plurality of spaced-apart heat
transfer elements have a diamond-shaped cross section;
means to move a first heat transfer past the first array and
means to move a second heat transfer fluid past the second
array.
20. A heat exchanger for use in a triple containment system wherein
heat production occurs in a first container and a first heat
transfer fluid is disposed within a second container with the heat
transfer fluid being in fluid communication with an exterior
surface of the first container, the second sealed container being
disposed within a third container that is sealed from an outside
environment, the heat exchanger comprising:
a first discrete conductive plate having a first surface with a
first plurality of spaced apart pins extending from the first
surface and a smooth second surface, wherein the first plurality of
pins are in heat transfer relationship with the environment;
a second discrete conductive plate having a first surface with a
second plurality of spaced apart points extending from a first
surface and a smooth second surface; wherein the second plurality
of pins are in a heat transfer relationship with the heat transfer
fluid of the second container, and the smooth side of the second
plate is in conductive heat transfer relationship with the smooth
side of the first plate.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to heat exchangers and, particularly,
the present invention relates to heat exchangers having a plurality
of heat conductive pins extending from a first surface wherein heat
is transferred between the pins and a heat transfer fluid flowing
past the pins.
2. Description of the Prior Art
U.S. Pat. No. 3,800,864 issued to Hauser et al. discloses a cooling
system for gas turbine engines including discrete pin-fins upon a
face of a wall bounding a hot gas passage. The discrete pin-fins
extend into a cooling fluid plenum.
U.S. Pat. No. 4,638,858 issued to Chu discloses heat conducting
pins or posts mounted in holes in a base to be cooled. The pins
carry heat conducting wings that extend oppositely in the upstream
and downstream direction of the flow of a coolant across the
base.
U.S. Pat. No. 3,964,286 to Oerther et al. discloses an apparatus
for bending fragile pin-fins on a finned tubed heat exchanger.
SUMMARY OF THE INVENTION
A heat exchanger includes a plate of heat conductive material
having a first major face and a second major face, an array of a
plurality of integral heat transfer elements projecting from the
first face, and a fan causing a flow of heat transfer fluid past
the heat transfer elements thereby transferring heat between the
heat exchanger and the heat transfer fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the heat exchanger of the present
invention in use.
FIG. 2 is a top view of the heat exchanger of the present invention
in use.
FIG. 3 is a side view of the heat exchanger of the present
invention.
FIG. 4 is a sectional view along the lines 4--4 of FIG. 2.
FIG. 5 is a sectional view along the lines 5--5 of FIG. 3.
FIG. 6 is a sectional view along the lines 6--6 of FIG. 3.
FIG. 7 is an enlarged sectional view to show additional detail of a
quadrant of FIG. 5.
FIG. 8 is a sectional view through a portion of a full rib of the
heat exchanger of this invention along the lines 8--8 of FIGS. 5
and 6.
FIGS. 9A and 9B are sectional views of alternative embodiments of
the present invention.
FIG. 10 is a graphical view of air velocity with respect to angular
position in a quadrant.
FIG. 11 is a graphical view of the performance of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The subject invention combines three important functions. First,
the invention serves to transfer heat. Second, the invention serves
as a structural part of a container. Third, the invention provides
a hermetic seal to a container closure.
In FIG. 1, a NASA Experimental Apparatus Container 20 (EAC) is
shown. The EAC 20 includes mounting brackets 24 and a cylindrical
wall 26. Additionally, a heat exchanger 30 of this invention is
installed upon the EAC 20 and replaces the cover supplied by NASA.
The heat exchanger 30 includes an upper fan housing 32. An
Electronics Module (not shown) may be used to control the EAC 20
and/or the heat exchanger 30. The Electronics Module (not shown)
may be external or may be internally disposed within the EAC
20.
FIG. 2 is a top view of the EAC 20 installed on a NASA Orbiter
Mid-deck wall 40. The mounting brackets 24 provide a rigid mounting
of the EAC 20 upon the Mid-deck wall 40. The heat exchanger 30 is
installed upon the EAC 20 and includes the upper fan housing
32.
The Orbiter Mid-deck wall 40 includes a plurality of locker spaces
42, which are generally of rectangular dimensions. The EAC 20
requires two mid-deck locker spaces 42 for mounting.
In FIG. 3, a side view of the EAC 20 mounted on the Orbiter
Mid-deck wall 40 is shown. Again, the EAC 20 includes the mounting
brackets 24 and the cylindrical wall 26. Additionally, installed
upon the EAC 20 is the heat exchanger 30. The heat exchanger
includes the fan housing 32.
The EAC 20 houses experiments involving chemical or materials
processing to be performed in the absence of gravity. Within a NASA
Space Shuttle, the Orbiter Mid-deck area 40 lies within an area
occupied by astronauts. To protect astronauts from harmful or toxic
materials which might be produced by such space experiments, some
chemical experiments performed in space are required to be housed
in an EAC 20, or other suitable container having a multiple
containment enclosure. For example, a triple containment enclosure,
by which is meant that an experiment is contained within a defined
first container (first level of containment) which, in turn, is
contained within a second container (second level of containment)
which, in turn, is contained within a final, third container (third
level of containment). Additionally, some or all of these
containers may be hermetically sealed. Many experiments tend to
generate heat. A drawback to the triple containment enclosure is
that it is also a barrier to heat transfer. In order to allow
efficient thermal regulation of experiments within the triple
containment enclosure of the EAC 20, the heat exchanger 30 of this
invention was developed.
FIG. 4 is a sectional view along the lines 4--4 of FIG. 2. The EAC
20 includes the cylindrical wall 26. The EAC 20 serves as the
third, or outermost level of containment, of the triple containment
enclosure. Within the EAC 20 is a second level of containment, a
second containment canister 50 (SCC). The SCC 50 includes a
cylindrical wall 52 which is coaxially located within the
cylindrical wall 26 of the EAC 20. The SCC 50 also includes a base
54 which is secured to an inwardly directed flange 56 of the EAC 20
by bolts 58. An innermost or primary container 61 is disposed
within the SCC 50. The primary container 61 provides the first
level of containment and is a source of heat. Further, other
components may be present within the SCC 50 including other heat
sources and other containers.
The heat exchanger 30 of this invention serves in part as a cover
on the EAC 20. The heat exchanger 30 includes a plate 100. The
plate 100 is formed of a heat conductive material. In a most
preferred embodiment, the plate 100 is formed of aluminum or an
aluminum alloy and is approximately 0.125 inches thick and has an
approximately 14 inch diameter. Alternatively, copper or other
suitable conductive materials can be used. The plate 100 has a
first major face 102 and a second major face 104.
Projecting from the first major face 102 are a plurality of an
integral heat transfer elements 110. Preferably, the plate 100 and
heat transfer elements 110 of the heat exchanger 30 are machined
from one piece of heat conductive material. The integral heat
transfer elements 110 are arranged in arrays 112. In a preferred
embodiment, the integral heat transfer elements 110 project
approximately 1.0 inch from the plate 100.
The heat exchanger 30 also includes at least one fan 120 which
drives a flow of the heat transfer fluid as generally indicated by
arrow 122, for example ambient air, parallel to the first major
face 102 of the plate 100 and past the elements 110. In a preferred
embodiment, the fan 120 is one of a set of four fans 120 which
directs air in a flow direction 122. In this embodiment, the flow
direction 122 of air is first driven toward the plate 100 and is
then directed substantially parallel to the plate 100.
The flow of air is confined by a panel 130 which serves as a
boundary defining in part a plenum space 132. The panel 130 is
spaced apart from the plate 100. In the preferred embodiment, the
panel 130 extends over the integral heat transfer elements 110
projecting from the first face 102 of the plate 100. Optionally, a
vibration damper 131 lies between the heat transfer elements 110
and the panel 130. Thus, the heat transfer fluid flow 122 is forced
into the plenum 132 by the fan 120. The flow 122 is in a generally
radial direction and contacts the integral heat transfer elements
110 projecting from the first face 102 of the plate 100. The
contact between the flow 122 of heat transfer fluid and the
integral heat transfer elements 110 allows heat to be transferred.
Because the heat transfer elements 110 are integral with the plate
100, heat is conducted from or to the second face 104 through the
plate 100 into the integral heat transfer elements 110 and then
transferred to or from the flow direction 122 of heat transfer
fluid. The flow direction 122 of heat transfer fluid exits the
plenum space 132 at a port 134. Thus, the ambient air serves as a
heat sink for the heat exchanger 30.
In an alternative arrangement, the fan 120 may operate to pull air
in the opposite direction, thereby reversing the flow 122. In this
alternative embodiment, air enters the plenum space 132 at the port
134, contacts the heat transfer elements 110 and exits
perpendicular to the plate 100 through the fan 120. This
alternative embodiment avoids any preheating of the air flow by the
fan motor. However, this alternative arrangement is not preferred
for use in the Space Shuttle for the following reason. A discharge
of air through the fan 120 tends to blow in an astronaut's face
which is undesirable.
The heat exchanger 30 further includes a seal ring assembly 136 at
the periphery of the plate 100. At the periphery of the seal ring
assembly 136 is a mounting rim 138 which mates with a mounting rim
140 at the terminus of the cylindrical wall 26 of the EAC 20. The
mating arrangement between the mounting rim 138 of the heat
exchanger 30 and the mounting rim 140 of the EAC 20 is maintained
by clamping means, specifically a band clamp 142. The band clamp
142 forces the mounting rim 138 tightly against mounting rim 140
when the circumference of the band clamp 142 is reduced. The band
clamp 142 and mounting flange arrangement 140 is a feature on NASA
provided EAC's 20. A similar clamping means or arrangement is also
present on the EAC 20 where the cylindrical wall 26 is joined to a
base member 144 by a second band clamp 146. Hermeticity is provided
by elastomeric O-rings 147 in both seals.
Thus, the heat exchanger 30 has a dual function. First, the heat
exchanger 30 serves as a heat exchanger transferring heat to or
from the second major face 104 to the heat transfer fluid of flow
122. Second, the heat exchanger 30 serves as a portion of the outer
containment system of the EAC 20.
In an especially preferred embodiment, a second similar heat
exchanger 170 is in a back-to-back arrangement with the first heat
exchanger 30. The second heat exchanger 170 has an integral plate
172 made of heat conductive material. Preferably the heat
conductive material is aluminum or an aluminum alloy.
Alternatively, copper or other suitable heat conductive materials
can be used. The plate 172 has a first major face 174 and a second
major face 176. The second major face 176 of the second heat
exchanger 170 is in a physical and heat conducting contact with the
second major face 104 of the first heat exchange unit 30.
A plurality of integral heat transfer elements 178 project from the
first face 174 of the plate 172. The second heat exchanger 170 also
includes at least one fan 180 which serves as a means to drive a
flow 182 of a heat transfer fluid, preferably a gas such as air or
nitrogen through a plenum space 186. The plenum space 186 is
bounded in part by the first major face 174 of the plate 172 and a
panel 184. The panel 184 and the first major face 174 are spaced
apart by the integral heat transfer elements 178. The flow of heat
transfer fluid as indicated by arrow 182 through a plenum 186
results in intimate contact between the heat transfer fluid and the
integral heat transfer elements 178.
As in the first heat exchange unit 30, the heat transfer elements
178 are arranged in a wedge-shaped array 188. Also, a flow, as
indicated by arrow 182, which begins at the fan 180 perpendicular
and inwardly toward the plate 172 and is then directed radially
outwardly, substantially parallel to the plate 172 through the
plenum 186, and exits through a port 190.
The second heat exchange element 170 serves as a structural member
of the SCC 50 and further serves to maintain hermeticity of the SCC
50. A flange 192 is located at the periphery of the plate 172. The
flange 192 is in mating contact with a flange 194 at the terminus
of the cylindrical wall 52 of the SCC 50.
Because the SCC 50 is a sealed system, the flow as indicated by
arrows 182 circulates through the SCC 50 and returns to the second
heat exchanger 170. Thus, the present invention, as used in this
embodiment serves to transfer heat resulting from the first
container 61 located within the SCC 50. Forced convection by the
fan 180 transfers heat to the integral heat transfer elements 178,
then by conduction to the plate 172. Heat is then conducted between
the second major face 176 of the plate 172 to the heat exchanger 30
of the EAC 20, across the interface between the second major face
176 of heat exchanger 170 and the second major face 104 of heat
exchanger 30. Heat is then conducted to the integral heat transfer
elements 110 of heat exchanger 30 and then forced convection of the
heat transfer fluid by fans 120 results in heat being transferred
to the heat transfer fluid, such as ambient air, of the Orbiter
Mid-deck.
In FIG. 5, a sectional view of the first heat exchanger 30 is shown
along the lines 5--5 of FIG. 3 with a portion or quadrant 200 shown
in detail. The first heat exchanger 30 is mounted on the EAC 20. A
fan 120 is associated with each quadrant 200 of the heat exchanger
30. Each fan 120 is mounted proximal to the apex 201 (center of
plate 100) of the quadrant 200. The heat exchanger 30 includes four
quadrants 200 disposed about a center 201. Within each quadrant
200, the integral heat transfer elements 110 are arranged in the
arrays 112. Each quadrant 200 contains a fan 120 and a pair of
arrays 112; preferably these arrays 112 are identical in each
quadrant 200.
Each quadrant 200 is defined by a pair of full ribs 202 that extend
radially outwardly. The full ribs 202 serve to support the panel
(130 of FIG. 4) and additionally serve as a boundary of the plenum
132 associated with each fan 120. Between the two ribs 202 is a
half rib 204. The half rib 204 also serves, in part, to support the
panel 130 and, in part, to split the flow (122 of FIG. 4) between
the pair of arrays 112. In the preferred embodiment, the full ribs
202 and half ribs 204 project approximately 1.0 inch from the plate
100.
The heat transfer elements 110 are diamond-shaped in a cross
section parallel to the first major face 174 in the preferred
embodiment. Other alternative shapes include circular or square
cross sections. The preferred diamond shape is based upon
consideration of the combination of ease of manufacture, static
pressure and heat transfer.
Further, in the preferred embodiment, the integral heat transfer
elements 110 within the arrays 112 are arranged in rows 203 and
columns 205. The most preferred embodiment of rows 203 and columns
205 involves rows 203 arranged parallel to the full ribs 202 and
columns 205 arranged parallel to the half ribs 204. The rows 203
and columns 205 intersect at approximately a 45.degree. angle. The
45.degree. angle is also the preferred angle for the preferred
diamond-shape of the integral heat transfer elements 110. Further,
the rows 203 and columns 205 are preferably spaced apart by
approximately 0.125 inch. This is slightly larger than the
preferred size of a face 207 of the diamond pin-fins 110, which is
approximately 0.10 inch. The faces 207 of the pin-fins 110
intersect at an angle of about 45.degree. for two opposing edges of
the pin-fins 110 and at an angle of about 135.degree. for the two
remaining edges of the pin-fins 110. The pin-fins 110 are aligned
so that the about 45.degree. angles are radially in line with the
flow 122 from the fans 120.
While not being bound by theory, the pin-fins 110 are highly
effective in transferring heat to the flow 122 of air, because:
first, the pin-fin 110 has a large surface area and a high fin
efficiency;
secondly, the array 112 of pin-fins 110 continually break up both
the thermal and hydrodynamic boundary layers, thus increasing the
heat transfer coefficient; and
thirdly, the preferred diamond-shaped pin-fin 110 and the preferred
alignment relative to the flow 122 accomplishes heat transfer with
minimal static pressure drop in the heat transfer fluid.
These factors improve mixing and heat transfer.
In FIG. 6, a sectional view taken along the lines 6--6 of FIG. 3 is
presented with a portion illustrated in detail. In this view, the
second heat exchanger 170, which is associated with the SCC 50, is
shown. The heat exchanger 170 has four fans 180 and is split into
four quadrants 300 by full ribs 302. The integral heat transfer
elements 178 are arranged in arrays 188. In the preferred
embodiment, the second heat exchanger 170 is nearly a mirror image
of the first heat exchanger 30 and is in physical contact, one heat
exchanger 170 with another heat exchanger 30 at the junction of
their respective faces 176 to 104.
The integral heat transfer elements 178 are again arranged in a
pair of arrays 188. The arrays 188 are separated by a half rib 304.
Both the half ribs 304 and the full ribs 302 serve to support the
panel 184 which defines the plenum 186 enclosing the arrays 188 of
the integral heat transfer elements 178. Within the arrays 188, the
heat transfer elements 178 are arranged again in rows 303 and
columns 305. The rows 303 and columns 305 are parallel to the full
ribs 302 and half ribs 304 which bound the arrays 188 of the heat
transfer elements 178. Further, the rows 303 and columns 305 are
spaced apart approximately 0.125 inch. The full ribs 302, half ribs
304 and heat transfer elements 178 all preferably project
approximately 1.0 inch from the plate 172. As with the plate 100 of
the first heat exchanger 30, the plate 172 of the second heat
exchanger 170 is preferably approximately 0.125 inch thick and has
a diameter of approximately 14 inches and is machined from a single
piece of aluminum. Again, a diamond-shaped cross section is
preferred for the heat transfer elements 178.
Additionally, the full ribs 302 defining each quadrant 300 serve as
boundaries of the plenum 186 of FIG. 4. The half rib 304
additionally serves to split the flow 182 of heat transfer fluid at
the boundary between the two arrays 188. The half ribs 304, and
ribs 204 of FIG. 5 as well, are important because the fans 180, and
fans 120 of FIG. 5, tend to produce a radial swirl component in the
flows 182 and 122, respectively, as illustrated in FIG. 4. The half
ribs 304, and half ribs 204 of FIG. 5, split the flows 182 and 122,
respectively, as illustrated in FIG. 4 between the paired arrays
188 and arrays 112, respectively.
FIG. 7 is an enlarged view of the detailed quadrant of FIG. 5. This
view again shows the pair of arrays 112 of the integral heat
transfer elements 110. The preferred embodiment of the heat
transfer element 110 is the diamond-shape which may be described as
a "pin-fin" 110. The pin-fins 110 are integral to the plate 100 and
project upwardly from the first major face 102. The diamond-shaped
pin-fins 110 have walls 207 parallel to the nearest full rib 202
and walls 207 parallel to the nearest half rib 204. The fan 120 is
located proximate to the apex 201 (center of plate 100) of the
quadrant 200. The array 112 is generally wedge-shaped with the
number of pin-fins 110 increasing in a direction distal to the fan
120.
The full ribs 202 and half ribs 204 are preferably approximately
0.413 inch wide and include a plurality of centered channels 203
which are approximately 0.283 inch wide. The full ribs 202 meet at
the center 201 of the plate 100 and help to add rigidity and
"stiffen" the heat exchanger.
In FIG. 8, a portion taken along the lines 8--8 of FIG. 5 is
presented which details the full ribs 202 of the first heat
exchanger 30 and full ribs 302 of the second heat exchanger 170.
The full rib 202 is integral with the plate 100, projecting from
the first major face 102. The upper surface of the rib 400 supports
the panel 130. The panel 130 is held in place by a number of
threaded fasteners or screws 402.
The rib 202 also includes channels 203 extending from the upper
surface 400 to the first major face 102. Seal screws 406 are used
in the channels 203 whenever openings 408 extend through the plate
100. The seal screws 406 are threaded into the rib 302 of the
second heat exchanger 170. The seal screws 406 serve to maintain
the heat conductive interface and physical contact between the
second major face 104 of plate 100 of the first heat exchanger 30
and the second major face 176 of the plate 172 of the second heat
exchanger 170.
Additionally, the seal screws 406 maintain a hermetic seal in the
EAC. The seal ring assembly 136 includes an O-ring 414 which
compensates for thermal expansion. An additional O-ring 416 is
compressed at the contact between the seal ring assembly 136 and
the plate 100. Together, O-rings 147, 414 and 416 provide a
hermetic seal for the EAC 20. Additionally, an O-ring 418 provides
a hermetic seal between the inner plate 172 and the SCC 50.
The surface 410 of the lower rib 302 supports the panel 184. The
panel 184 is attached to the rib 302 by screws 412. The fan housing
32 is attached to the rib upper surface 400 by screws 403 and
serves to protect the astronauts from contact with the fan 120. The
internal fans 180 of the second heat exchanger 170 lack an
equivalent protective covering to the exterior covering 32.
The full ribs 302 of the second heat exchanger 170 also include
channels 303. The channels 303 are mirror image equivalents of the
channels 203 with a single exception: the channels 303 are left
solid opposite the sealing screws 406. Threaded receiving holes 305
extend inwardly from the second face 176 such that the heat
exchangers 30 and 170 may be fastened together in the preferred
back-to-back arrangement. The threaded receiving holes 305 are
blind holes such that they do not breach the SCC 50.
An alternative embodiment 501 of the present invention is
illustrated in FIGS. 9A and 9B. The embodiment 501 is suitable for
use as a portion of an individual containment canister such as the
EAC 20, but without functioning as part of a second level of
containment. In such an arrangement, other containment canisters
may be optionally present, but remain independent of the heat
exchanger 501. The embodiment 501 includes a single heat conductive
plate 500 having a first major face 502 and a second oppositely
facing major face 503. The alternative single plate is preferably
approximately 0.125 inch thick and approximately 14 inches in
diameter. Projecting from the first major face 502 are a plurality
of integral heat transfer elements 504.
Preferably each of the integral heat transfer elements 504 have a
diamond-shaped cross section and are arranged in a wedge-shaped
array 506 of rows and columns parallel to ribs (not shown) in an
arrangement similar to the arrangement illustrated in FIGS. 5 and
6. The face 502 is divided into quadrants and each quadrant is
associated with a fan 508 and has a pair of arrays 506 separated by
a half rib (not shown). The fan 508 is located inside a fan housing
510 and serves to drive a flow 512 of heat transfer fluid, such as
air, through a plenum 516. The plenum 516 is bounded by a panel 518
and the first major face 502 of the plate 500.
Projecting from the second major face 503 of the plate 500 are a
plurality of integral heat transfer elements 530. Each of the heat
transfer elements 530 have a diamond-shaped cross section and are
arranged in a wedge-shaped array 532 of rows and columns. A pair of
the arrays 532 are located within each quadrant. Each quadrant is
associated with a fan 534 which drives a flow of heat transfer
fluid as indicated by arrow 533, such as air, through a plenum 536.
The plenum 536 is defined in part by a panel 538 and in part by the
second major face 503 of the plate 500. Additionally, the plenum
536 is defined by full ribs (not shown) and segmented between the
pair of arrays 532 by a half rib (not shown).
The rib (not shown) is integral with the plate 500 projecting from
the first major face 502 and also from the second major face 503.
The rib (not shown) serves as a mounting point for the panels 518
and 538 as well as the fan 508 within the housing 510 and the lower
fan 534. About the periphery of the plate 500 is a mounting flange
550 which mates with mounting flange 140 of the EAC 20, at the
terminus of the cylindrical wall 26. The flange 550 is held in
mating arrangement with the flange 140 by the band clamp 142. Thus,
this embodiment 501 forms a hermetic container providing a single
level of containment by compression of the O-ring seal 147.
For testing heat transfer capabilities and air flow measurements,
two slabs of approximately 1.25 inch thick 6061-T6 aluminum were
used to form a pair of single quadrant heat exchangers. Spaces were
milled out to form the array of columns and rows of pin-fins, as
well as the full and half ribs, resulting in a pair of quadrant
(pie-shaped) plates with an approximately 7 inch radius. The smooth
faces of the 0.125 inch thick plates were hand lapped to such an
extent that the faces were less than 0.001 of an inch from
theoretic flatness. The pair of heat exchangers were assembled in a
back-to-back manner.
The two quadrants each included a pair of arrays of diamond-shaped
pin-fins as shown in FIG. 7. Each pin-fin was approximately 1.0
inch high and the air gap between the pin fins was approximately
0.125 inches.
A box fan was mounted on each side of the plates, near the apex of
the quadrants, and used to drive air past the pin-fins. The box fan
included a brushless D.C. motor. A full speed load for this fan was
2.1 watts at 28 VDC. The fan was 0.792 inches thick and weighed
0.31 pounds. The box fan delivered 17 cfm of air at 0.05 inches of
water column static pressure. Air velocity through the pair of
arrays of pin-fins in the quadrant was measured along the
circumference of the plenum space. The results for three different
voltages applied to the box fan are presented in FIG. 10.
In FIG. 10, the measured air velocity in feet per minute is plotted
as a function of angular position between the two ribs defining the
quadrant. The uppermost curve 600 represents the air velocities
measured when 28 volts was applied to the box fan. The middle curve
602 represents the air velocities measured when 24 volts was
applied to the box fan. The lower curve 604 represents the air
velocities measured when 20 volts was applied to the box fan. The
graph also presents the location of the full ribs 606 and the half
rib 608 for reference in relationship to the air velocity
curves.
In general, the more uniform the flow, the more efficient the array
of pin-fins will be in transferring heat.
The data in FIG. 10 indicates that the flow of air occurs over the
entire array of pin-fins. However, a slight decrease in air flow is
observed from 90.degree. to 0.degree. of a quadrant. This slight
decrease is explained by the fact that the fan is located at the
apex of the quadrant and that the impeller rotates in a clockwise
direction. This arrangement creates a higher static pressure near
the full fin located at 90.degree.. The half rib at 45.degree.
serves in part to minimize this effect. Flow peaks are observed
near the ribs and represent relatively unimpeded air flow along the
full and half rib walls.
The ratio of air passing the two arrays in the quadrant is
approximately 1.0:1.5. This is an acceptable ratio, since heat
transfer is known to be a function of the square root of flow
velocity. Thus, the ratio of heat transfer between the two arrays
is approaching 1.0:1.2. The actual ratio, however, is somewhat
higher than 1.0:1.2, since the flow velocity also contributes to
the heat capacity of the air flow. Although the flows across both
arrays may be equalized by installing a flow restricting screen or
similar device, it is believed that solution would be detrimental
since the gain would be marginal due to increased static pressure
on the fan and a resulting lower flow rate.
The combined back-to-back single quadrant heat exchanger was also
tested for its heat transfer capabilities. The test involved
thermally isolating a source of heat such that the back-to-back
heat exchanger represented the only heat pathway.
Specifically, the heat exchanger assembly was mounted on a 3/8 inch
plexiglass plate insulated with one inch of rigid insulation. The
plexiglass plate was placed on a container with the second heat
exchanger facing inward. The container was insulated with 4 to 6
inches of fiberglass insulation. A resistive heating element was
included within the insulated container to serve as a heat input.
Thermocouples were used to measure the temperature on both sides of
the heat exchanger. A 25 watt heat load was simulated by the
combination of the resistive heater and the internal fan. Both the
fans were operated at 24 VDC. The heat exchanger equilibrated at a
temperature differential of about 10.degree. C. Tests with an
insulated cover and heat exchanger suggest that the system
contributed a temperature differential of about 2.degree. C. Thus,
the single quadrant heat exchanger transferred 25 watts (resistive
heat and internal fan) at a temperature differential of 12.degree.
C. when 24 VDC was applied to the fans. These data, along with data
from tests at other resistive inputs, are presented in FIG. 11. The
heat inputs in watts and the temperature differentials associated
with the heat inputs (at equilibrium) are plotted and a best line
drawn 702. The heat inputs and temperature differentials, at
equilibrium, resulting when a fully insulated cover is substituted
for the heat exchanger are plotted and a best line drawn 704.
Subtracting line 704 from line 702 indicates the heat transfer
capabilities of the quadrant heat exchanger at line 706.
Based upon the data from the single quandrant heat exchanger, the
capabilities of a four quadrant back-to-back heat exchanger are
estimated to be 100 watts continuously transferred from the SCC to
the Orbiter cabin air at 24.0 VDC operation. Additionally, the four
external fans produce 6.4 watts. Therefore, 106.4 watts of heat is
discharged into the Orbiter cabin air when a 100 watt source is
maintained at a temperature differential of 12.0.degree. C. between
the SCC environment and the Orbiter air. The four external fans
generate a 55 CFM flow across the pin-fin arrays. The noise level
is less than 40 dB-A.
The configuration shown in FIGS. 1-8 adds approximately 9.1 pounds
to a similar containment device lacking a heat exchanger.
Although the present invention has been described with reference to
preferred embodiments, workers skilled in the art will recognize
that changes may be made in form and detail without departing from
the spirit and scope of the invention.
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